242 A HISTORY OF FISHES 



and found that, as a general rule, few were able to endure water 

 that was hotter than about 99° F., and that cold was resisted 

 much more easily than heat. The fishes were found to behave 

 in a perfectly normal manner in water heated up to 73'' to 75° F., 

 their breathing was affected at 93°, a loss of equilibrium 

 occurred at 99°, coma and convulsions at 106° to 109°, and 

 death supervened when the temperature reached 113° to 116°. 

 In the reverse experiment, the fish were normal until the 

 water reached 64°, breathing movements were exaggerated 

 at 60° to 57°, much affected at 53.5° to 50°, equilibrium was 

 upset at 43° to 39°, convulsions occurred at 37.5° to 35.5°, 

 followed by death before freezing-point was reached. The 

 power of resistance to heat or cold varies considerably in 

 different fishes, but it is a little difficult to explain why some 

 species should be so much more easily affected than others. 

 It is clear that those fishes which are less sensitive to change of 

 temperature are most easily acclimatised in new countries, 

 and for this reason the Carp (Cyprinus) and some of its allies, 

 such as the ubiquitous Gold-fish (Carassius) thrive equally well 

 in tropical and temperate countries. This is not to say that 

 they can stand a sudden and violent change in the temperature 

 of the water, and ignorance of this fact has led to the death of 

 many a pet Gold-fish, which has met its end through being 

 plunged suddenly into fresh cold water from the tap during the 

 process of cleaning the bowl or aquarium. Salmon and Trout 

 (Salmo) bear transplantation fairly well so long as the water is 

 clear and rather cold, but the closely related Grayling {Thy- 

 mallus) is highly sensitive to the slightest change in its 

 conditions. 



A curious and interesting example of a marine catastrophe, 

 believed to be due to such a climatic cause as a sudden influx of 

 cold water, was provided in 1882 by the Tile-fish (Lopholatilus) , 

 an inhabitant of the deep water below the Gulf Stream in the 

 Atlantic (Fig. 94B). This species was unknown in 1879, but 

 in the following year was found to be extremely abundant 

 everywhere off the coast of southern New England at a depth of 

 from seventy-five to two hundred and fifty fathoms below the 

 surface. Numerous specimens, varying from ten to fifty 

 pounds in weight were captured, and as the flesh was well 

 flavoured, the Tile-fish became the object of an extensive 

 American fishery with long lines. In March 1882, however, 

 following heavy gales, millions of these fishes were to be seen 

 floating dead at the surface of the water, covering an area of no 



